Java nullpointer Exception: cannot invoke "com.razorpay.Order.toString()"because "order" is null

Question

package com.example.demo.controller;

import com.example.demo.entities.Users;
import com.example.demo.services.UsersService;
import com.razorpay.Order;
import com.razorpay.RazorpayClient;
import com.razorpay.RazorpayException;
import jakarta.servlet.http.HttpSession;
import org.json.JSONObject;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.ResponseBody;

@Controller

public class PaymentController {
  @Autowired UsersService service;

  @GetMapping("/pay")
  public String pay() {
    return "pay";
  }

  @SuppressWarnings("finally")
  @PostMapping("/createOrder")
  @ResponseBody
  public String createOrder(HttpSession session) {
    int amount = 5000;
    Order order = null;
    try {
      RazorpayClient razorpay = new RazorpayClient(
          "rzp_test_pvGIc9JvXWZTVS", "UlnLCUb8lRxvBKRyIYRYWrEO");

      JSONObject orderRequest = new JSONObject();
      orderRequest.put(
          "amount", amount * 100); // amount in the smallest currency unit
      orderRequest.put("currency", "INR");
      orderRequest.put("receipt", "order_rcptid_11");

      order = razorpay.orders.create(orderRequest);

      String mail = (String) session.getAttribute("email");

      Users u = service.getUser(mail);
      u.setPremium(true);
      service.updateUser(u);

    } catch (RazorpayException e) {
      e.printStackTrace();
    } finally {
      return order.toString();
    }
  }
}